Implement carrying linkages for excavators and other similar machines may include multiple load bearing structures, such as a boom and/or a stick, which may be fabricated from a number of steel plates joined together by welds forming a box beam (also referred to as a box section). The box beam includes a hollow region enclosed by the steel plates. The box beam structures may be subjected to torsional loads during use of the machine, which may result in deformation and/or failure the box beam structure.
One solution to provide enhanced rigidity to a box beam structure subject to torsional loads is to weld baffle plates within the box beam at various locations. However, manufacturing a box beam structure having such internally welded baffle plates requires a significant amount of tooling, welding equipment, and process time. Additionally, because the baffle plates are internal to the structure, visual inspection and repair of the baffle plate welds require cutting into the box beam to access the baffle plates and their associated welds then repairing the box beam after the inspection and/or repair has been completed.
U.S. Pat. No. 5,152,659 discloses increasing torsional rigidity of an excavator boom by including a cylindrical cross-tie member penetrating through and welded to the side plates of the boom assembly. However, the cylindrical cross-tie member does not provide for diffusion of torsional loads or distribution of the loads into the boom structure.
U.S. Pat. No. 4,439,089 discloses a loader boom arm assembly having a pair of box section boom arms and a cross tube welded to the inboard sidewalls of each of the box section boom arms. In this configuration, the cross tube is not enclosed within a structure and simply provides a rigid connection between two box section boom arms.
Japanese Patent JP 59170332A discloses construction of a boom without reinforcing plates or partition walls by welding upper and lower intermediate brackets to the left- and right-handed boom cylinder brackets. However, this configuration is internal to the box section and would require removal of the boom cylinders and/or cutting into the box section to inspect and/or repair the welds.
The disclosed apparatus and method for reinforcing a load bearing structure is intended to overcome one or more of the problems set forth above and/or other problems of the prior art.